COMPEL? are highly uniform superparamagnetic microspheres ideal for applications that demand uniform particle response, such as miniaturized bioassays, suspension arrays, and separations. COMPEL? are comprised of iron oxide crystals dispersed in a polymer matrix, with a functional polymer overcoating for the encapsulation of magnetite and the introduction of reactive groups. As they are polymer-based, they retain the low density that is advantageous for biomolecular assays.nAvailable in 3, 6, and 8 μm diameters.